From 8210a58044d1e6d86473fdf810396d285c86ff36 Mon Sep 17 00:00:00 2001
From: Fabrice de Gans <Steelskin@users.noreply.github.com>
Date: Thu, 11 Jun 2026 09:48:04 +0000
Subject: [PATCH] [Demangle] Guard DEMANGLE_ABI and add missing annotation
 (#202920)

This updates the DEMANGLE_ABI annotation to only be defined if it is not
already defined. This is required to parse the Demangle headers with the
ids-check script.
In addition, this adds one missing DEMANGLE_ABI annotation.

This effort is tracked in #109483.
---
 libcxxabi/src/demangle/Utility.h            |  2 +-
 llvm/include/llvm/Demangle/DemangleConfig.h | 39 ++++++++++++---------
 llvm/include/llvm/Demangle/Utility.h        |  2 +-
 3 files changed, 24 insertions(+), 19 deletions(-)

diff --git a/libcxxabi/src/demangle/Utility.h b/libcxxabi/src/demangle/Utility.h
index df5b54dca492..ca420bce66d9 100644
--- a/libcxxabi/src/demangle/Utility.h
+++ b/libcxxabi/src/demangle/Utility.h
@@ -31,7 +31,7 @@ class Node;
 
 // Stream that AST nodes write their string representation into after the AST
 // has been parsed.
-class OutputBuffer {
+class DEMANGLE_ABI OutputBuffer {
   char *Buffer = nullptr;
   size_t CurrentPosition = 0;
   size_t BufferCapacity = 0;
diff --git a/llvm/include/llvm/Demangle/DemangleConfig.h b/llvm/include/llvm/Demangle/DemangleConfig.h
index 5c48ae1972be..9cd85efbbd23 100644
--- a/llvm/include/llvm/Demangle/DemangleConfig.h
+++ b/llvm/include/llvm/Demangle/DemangleConfig.h
@@ -97,24 +97,29 @@
 #define DEMANGLE_NAMESPACE_BEGIN namespace llvm { namespace itanium_demangle {
 #define DEMANGLE_NAMESPACE_END } }
 
-/// DEMANGLE_ABI is the export/visibility macro used to mark symbols delcared in
+/// DEMANGLE_ABI is the export/visibility macro used to mark symbols declared in
 /// llvm/Demangle as exported when built as a shared library.
-#if defined(LLVM_BUILD_STATIC) || !defined(LLVM_ENABLE_LLVM_EXPORT_ANNOTATIONS)
-#define DEMANGLE_ABI
-#else
-#if defined(_WIN32) && !defined(__MINGW32__)
-#if defined(LLVM_EXPORTS)
-#define DEMANGLE_ABI __declspec(dllexport)
-#else
-#define DEMANGLE_ABI __declspec(dllimport)
-#endif
-#else
-#if __has_attribute(visibility)
-#define DEMANGLE_ABI __attribute__((__visibility__("default")))
-#else
-#define DEMANGLE_ABI
-#endif
-#endif
+// clang-format off
+// Autoformatting removes indentation, making this harder to read.
+#if !defined(DEMANGLE_ABI)
+# if defined(LLVM_BUILD_STATIC) || !defined(LLVM_ENABLE_LLVM_EXPORT_ANNOTATIONS)
+#  define DEMANGLE_ABI
+# else
+#  if defined(_WIN32) && !defined(__MINGW32__)
+#   if defined(LLVM_EXPORTS)
+#    define DEMANGLE_ABI __declspec(dllexport)
+#   else
+#    define DEMANGLE_ABI __declspec(dllimport)
+#   endif
+#  else
+#   if __has_attribute(visibility)
+#    define DEMANGLE_ABI __attribute__((__visibility__("default")))
+#   else
+#    define DEMANGLE_ABI
+#   endif
+#  endif
+# endif
 #endif
+// clang-format on
 
 #endif
diff --git a/llvm/include/llvm/Demangle/Utility.h b/llvm/include/llvm/Demangle/Utility.h
index afdc1a397ca6..56c052e6a2cf 100644
--- a/llvm/include/llvm/Demangle/Utility.h
+++ b/llvm/include/llvm/Demangle/Utility.h
@@ -31,7 +31,7 @@ class Node;
 
 // Stream that AST nodes write their string representation into after the AST
 // has been parsed.
-class OutputBuffer {
+class DEMANGLE_ABI OutputBuffer {
   char *Buffer = nullptr;
   size_t CurrentPosition = 0;
   size_t BufferCapacity = 0;